Means for cleaning and cooling grinding apparatus



June 21, 1966 N. H. HUTTON 3,255,547

MEANS FOR CLEANING AND COOLING GRINDING APPARATUS Filed July 24, 1963 2Sheets-Sheet 1 M FIG. Ia

NORMA/V H. HUTTO/V BY WZMQ M ATTORNEYS INVENTOR June 21, 1966 N. H.HUTTON 3,256,647

MEANS FOR CLEANING AND COOLING GRINDING APPARATUS Filed July 24, 1965 2Sheets-Sheet 2 INVENTOR NORMA N H. HU T TON BY WWW ATTORNEYS UnitedStates Patent 3,256,647 MEANS FUR CLEANING AND COOLING GRINDENGAPPARATUS Norman Horatio Hutton, Hove, England, assignor to HydrolChemical Company Limited, Brighton, England, a corporation of GreatBritain Fiied July 24, 1963, Ser. No. 297,279 Claims priority,application Great Britain, Aug. 19, 1960, 28,800/ 6th 8 Claims. (Cl.51-467) This is a continuation-in-part of now abandoned applicationSerial No. 131,759, filed August 16, 1961. p

This invention relates to the grinding of metals, ceramics and othermaterials which have to be subjected to abradin-g in the course ofmanufacture and has for its object to provide an improved constructionor arrang ment designed to ensure the removal of accumulated debrisincluding swarf, gritty material and other waste substances removed froma work-piece by abrasion and which would tend in the course of time toimpede the grinding operation or cause deterioration of the surface of agrinding element.

It is also an object of the invention to provide means for ensuring theremoval of the waste substances under all conditions of wear on thegrinding element.

To avoid the disadvantages and to achieve the objects referred to in thepreceding paragraphs the present invention provides a grindingarrangement having a jet or jets for the introduction of grinding fluidadditional to the normal supply of fluid to a work-piece and so arrangedthat the fluid impinging on the surface of a rotary grinding elementwill loosen any solid deposits and thereby maintain the surface of thegrinding element clean and facilitate the ultimate removal of wastematerial 'from the grinding apparatus.

Reference will now be made to the accompanying drawings which illustratediagrammatically and by way of example, arrangements according-to theinvention and in which:

FIGURE 1 illustrates in elevation one construction according to theinvention and FIGURE 1a is a fragmentary elevation of a modifiedconstruction;

FIGURE 2 is an elevation illustrating a further modification; and

FIGURE 3 illustrates a modification of the adjust-able deflector plateshown in FIGURE 2.

Referring first to FIG. 1, a rotary grinding wheel a is disposed withina hood b shaped to enable a workpiece cI to be brought into contact withthe grinding wheel at c in the usual manner. Hood b essentially is ofconventional construction having a semi-circular, uniformly diameteredplate portion b1 and depending flat sided parallel skirt portions b2 andb3. Portion bit is radially spaced from the periphery of wheel a andportions b2 extend over opposite sides of the grinding wheel as shown.The space between hood port-ion b1 and the periphery of wheel a is maderelatively narrow for a purpose to be presently explained in detail.

A suitable nozzle 02 disposed externally of hood b conventionally isadapted to supply coolant liquid to the region where workpiece c1engages the periphery of grinding wheel a. In such an arrangement asnormally employed centrifugal force set up by the rotation of thegrinding wheel tendsto dislodge residues from the grinding wheel butalso to cause such residues to accumulate against the interior surfacesof the hood b. If these residues become detached from the interiorsurfaces of the hood and fall upon the grinding wheel they will detractfrom the efficient cutting action of the abrasive surfaces of the wheel.To avoid this happening, the present ice invention provides additionalmeans other than at the point c where the workpiece is actually abradedto detach the debris from the grinding face of the wheel a and preventthe accumulation of grinding residues within the hood b.

The means employed for removing debris as shown in FIGURE 1 comprises aliquid coolant supply system having a discharge conduit (or a number ofdischarge conduits) a disposed in the upper part of the hood I) and towhich the coolant fluid is supplied by the action of a pump 2 whichwithdraws the fluid from a storage tank f and passes it through a pipe gto the conduit d which is provided with a control valve h. As shown,conduit d comprises a straight tube d1 extending radially into hoodportion b1 and terminating in a nozzle or jet i within the confinedspace between hood portion b1 and the periphery of wheel a. Preferably,nozzle i is located at a point in the hood portion 121 remote from thework piece and opens to direct the liquid coolant jet radially inwardly.The fluid is pumped through the nozzle 1 at such temperature andpressure as to eject coolant liquid in the form of a jet whose impact onthe surface of the grinding wheel causes the debris to be dislodged fromthe grinding surface whilst atomization of the grinding fluid induced bythe rotation of the abrasive wheel will counteract any tendency of thedebris to accumulate and become attached either to the wheel or to theinterior of the hood. By thus maintaining the debris in a finely dividedand mobile condition, its removal with the grinding fluid as it leavesthe apparatus is ensured. The control valve 11 enables the volume ofgrinding fluid-to be adjusted to suit the character of the material ofthe work-piece under treatment.

Where a grinding wheel of substantial width is employed, the jet andnozzle may be disposed at one side of the hood so as to project theliquid transversely across the surface of the wheel. Alternatively, asshown in FIG- URE 1a additional coolant nozzles may be employed asindicated at k.

When dealing with metals such as cast iron or alloys thereof whichproduce a large quantity of waste residue during grinding, it may bedesirable to employ an additional pump in the tank 1 to boost thepressure at the nozzle or nozzles.

The arrangement above described in addition to ensuring removal of wasteresidues possesses the further advantage that the wetting by thegrinding fluid of the wheel surface and subsequent absorption of thefluid into the matrix and interstices of the wheel produces conditionswhereby the temperature in the cutting area at c is red-uced by thepreviously absorbed grinding fluid travelling out-wards by centrifugalforce between the wheel and the work-piece. The reduction of temperaturein the cutting area in conjunction with the re-absorption of coolantdeflected by hood [2 onto the periphery of the grinding wheel tends toavoid distortion of the work-piece or metallurgical change and inaddition promotes detachment of debris by contraction while residualcoolant will be cushioned between the wheel and the Work-piece to lowerthe cutting temperature. 1

The explanation of the results above described is that coolant liquiddirected on to the surface of a grinding (ii) The coolant liquid must beable to penetrate sufliciently into the surface of the grinding wheel toprevent it from becoming overheated and eventually distorted.

In obtaining the foregoing results, coolant liquid is introduced throughthe additional nozzle i within hood a as previously described. Owing tothe narrow space between the peripheral surface of the grinding wheeland the inner surface of hood position b1, the liquid introduced throughthe nozzle i is not immediately lost but due to its velocity and thespeed of rotation of the wheel the liquid rebounds or ricochets betweenthe two opposed surfaces as indicated at d2 and is thus brought intorepeated and intimate contact with the surface of the wheel, therebycooling that surface sufliciently to loosen the accumulated debris whichis eventually washed away as the liquid finally flows out of the spacebetween the hood and the wheel. This operation overcomes a longstandingdisadvantage as, due to the heating of the wheel under normal operationconditions, the particles of debris become tightly lodged in the smallinterstices in the rough surface of the wheel. The additional degree ofcooling imparted by the arrangement according to the present inventioncauses a sufficient degree of contraction to occur in the wheel surfacefor the jet of coolant to dislodge the particles leaving the surface ofthe wheel cooled and in good grinding condition.

The grinding arrangements above described also possess the advantage ofreducing the need for dressing the abrading surface resulting in morecontinuous production, higher output and better surface finishes thanhave been possible with arrangements hitherto employed.

In the modified construction shown in FIG. 2, a rotary grinding elementa is disposed within a housing or hood [2' with means external theretofor bringing a workpiece c1 into contact with the grinding surface asdescribed with reference to FIG. 1. Coolant liquid is directed by anozzle c2 onto the area of contact between the workpiece c1 and thegrinding element a in the normal manner and in addition a dischargeconduit d for coolant liquid is also arranged within the hood b fordirecting such liquid either radially or tangentially onto the surfaceof the grinding element over an area remote from the position of theworkpiece Hood b and conduit d are respectively of the same constructionas hood b and conduit d with like reference characters identifying likeelements. It has been found in practice that as the diameter of thegrinding element a becomes reduced by wear, the operation of theadditional jet of liquid from conduit d becomes progressively lesseffective in producing the conditions within the hood which arenecessary for adequate removal of debris and penetration of the grindingsurface by the coolant liquid. To deal with this difficulty the presentinvention provides a deflector l conveniently in the form of a plate ofcurvature concentric with that of the grinding element and hood withinwhich the deflector plate is adjustably mounted so that it can be movedat intervals to maintain a position in predetermined concentricrelationship with the grinding element a as the diameter thereofgradually decreases during use.

A convenient mode of mounting the deflector plate is to form at itscentre a sleeve m which passes adjustably over tube d of conduit d whichextends to the exterior of the hood b and through a guide or bracket 12mounted on the hood and carrying a set-screw 0 or equivalent devisearranged to bear upon the exterior of the sleeve in and retain it in anydesired position of adjustment. Thus, in the initial stage ofoperations, the deflector plate I can occupy a position in contact wtihthe inner surface of the hood and thereafter by slackening the set screw0 the deflector plate I and conduit d can be moved inwards at intervalsto maintain them in approximately constant spacing from the grindingwheel surface, their position being maintained by tightening theset-screw 0 after each each adjustment.

As the diameter of the grinding wheel is decreased by wear its peripheryceases to be concentric with the deflector plate and in addition to theadjustment already described it is preferable to employ the push rods 1)and p shown in FIG. 2. These push rods are mounted in sleeves q and qcarried by the hood b through which they project so that as thedeflector plate is moved inwards pressure can also be applied to thepush rods to bend the ends of the deflector plate to increase itscurvature and maintain it in substantially concentric relationship withthe grinding whel. The push rods can be secured in their adjustedposition by clamping screws 1' and r' passing through the sleeves q andq and carrying wing rods s and s for manual operation.

The deflector plate I must be so arranged as to ensure ricochet of thejet stream and diffusion on to the peripheral area. This can becontrived in two ways:

(a) An increase in velocity of the jet stream by additional pressure.

(b) Moving the jet, with or without the deflector, sufficiently near tothe periphery to ensure impingement and rebound.

Further the deflector plate I can be interchangeable so as toapproximate the radius of the grinding element as it wears away by theprocess of abrasion. Alternatively, a compromise solution by using asingle deflector plate could be used, the radius of which would be basedon the estimated diameter of the grinding wheel at the termination ofits useful life. For instance with a 24" diameter wheel, the radialdistance to the periphery of the wheel would be 12". The radius of thedeflector would be made to conform to the estimated diameter of itsuseful life, which would be estimated to be 18" in diameter. The radiusof the deflector would thus be made to conform to a wheel size ofapproximately 18". This would be adjusted to suit a new wheel so as to aensure the extreme ends of the deflector to maintain a small workingclearance of approximately a sixteenth of an inch.

The arrangement shown in FIG. 2 ensures that the jet stream is alwaysdirected where it will penetrate the air flow generated by the highspeed of the grinding wheel and thereby make contact with the wheelperiphery with sufficient force to enter the surface pores of the wheel.Owing to the narrow space which is maintained between the surface of thegrinding wheel and the inner surface of the deflector, the coolantliquid introduced through the jet in the plate is not immediately lost,but due to its velocity and the speed of rotation of the wheel, theliquid rebounds or ricochets between the surfaces of the wheel and theplate and is thus brought into repeated and intimate contact with thesurface of the wheel, thereby cooling that surface sufliciently toloosen the accumulated debris which is eventually washed away as theliquid flows out of the space between the deflector plate and the wheel.This operation overcomes the disadvantage hitherto experienced that dueto the heating of the grinding wheel under normal operating conditions,particles of debris become tightly lodged in the interstices in therough surface of the wheel. The additional cooling imparted by thearrangement according to the invention causes a suflicient degree ofcontraction to occur within the grinding wheel surface for the jet ofcoolant to dislodge the particles embedded and leave the surface of thewheel cooled and in good grinding condition.

The invention possesses the further advantage that the cooling of thegrinding wheel surface and its preservation in a good grinding conditionmaintains efficient operation and prevents overheating, distortion ordeterioration of the workpiece.

The hood above described may embody two stationary baffles arranged todeflect surplus liquid which is caused to fall through the base of thehood thereby protecting the operator from such liquids being thrownoutwards by rotation of the wheel in the region of the workpiece.

Referring now to FIGURE 3, a further modification resides in theprovision of a slot f in the deflector plate to allow coolant to passinto the space external to the deflector plate and operate to remove anydebris which may tend to accumulate on the inner surface of the hood.

What is claimed is:

1. In grinding apparatus, a rotatably mounted grinding element, meansfor supplying coolant liquid to the grinding area where a workpiece isbrought into contact with said element, a hood partially enclosing saidgrinding element, a nozzle mounted in the hood for directing a jet ofcoolant liquid against the periphery of said grinding element withinsaid hood, a curved deflector plate mounted within the hoodconcentrically with the grinding element, means for adjusting thepositions of said nozzle and deflector plate, said means for adjustingthe position of said deflector plate being effective to enable theradial distance of the space between said deflector plate and theperiphery of the grinding element to be varied as the diameter of saidgrinding element becomes reduced by wear and means for securing the saidnozzle and deflector plate in their adjusted positions.

2. In grinding apparatus as defined in claim 1, the provision of asleeve formed on the deflector plate and engaging over said nozzle whichprojects through to the interior of the deflector plate, a bracket onthe exterior of the hood through which said sleeve and nozzle pass andmeans carried by said bracket for engaging and locking the sleeve andnozzle in adjusted positions.

3. In a grinding apparatus having a rotatably mounted grinding wheel,hood means partially receiving said grinding wheel and having adeflector surface facing and spaced from the periphery of said wheel todefine a narrow space therewith, means providing a supply of liquidcoolant, a nozzle connected to said supply and disposed in said space todirect a jet of coolant liquid of predetermined velocity against theperiphery of said grinding wheel covered by said hood means to penetrateinto the periphery of said grinding wheel, said nozzle and deflectorsurface being so arranged that said jet repeatedly rebounds back andforth between said deflector surface and said wheel over a predeterminedperipheral segment of said wheel in said space.

4. The grinding apparatus defined in claim 3 wherein said nozzle extendsthrough said hood ,means and is so positioned as to direct said jetradially inwardly.

5. The grinding apparatus defined in claim 4 wherein said hood meanscomprises a hood and curved plate flector surface for radialdisplacement independently of each other to compensate for wear of saidwheel.

8. In a grinding apparatus having a rotatably mounted grinding wheel, ahood partially receiving said grinding wheel and being spaced from theperiphery thereof, plate means disposed radially between said hood andthe periphery of said grinding wheel and having a curved deflectorsurface facing and concentrically spaced radially from the periphery ofsaid grinding wheel to delimit a narrow space therewith, means providinga supply of liquid coolant, a nozzle connected to said supply of liquidcoolant and disposed in said narrow space to direct a jet of coolantliquid of predetermined velocity against the periphery of said grindingwheel covered by said hood, said nozzle and said deflecting surfacebeing so arranged that said jet repeatedly rebounds back and forthbetween said deflector surface and the periphery of said grinding wheelover a predetermined peripheral segment of said grinding wheel in saidnarrow space, and means adjustably mounting said plate means for radialdisplacement relative to said grinding wheel to enable the radialdistance of said narrow space to be varied to compensate for wear ofsaid wheel.

References Cited by the Examiner UNITED STATES PATENTS 385,666 7/1888Hadley 51-267 2,307,019 1/1943 Cebik 51-267 2,361,550 2/1944 Krueger5l-'272 3,123,950 3/1964 Kuris et al. 51-267 X FOREIGN PATENTS 701,2201/ 1941 Germany.

ROBERT C. RIORDON, Primary Examiner.

LESTER M. SWINGLE, Examiner.

I. A. MATHEWS, Assistant Examiner.

1. IN GRINDING APPARATUS, A ROTATABLY MOUNTED GRINDING ELEMENT, MEANSFOR SUPPLYING COOLANT LIQUID TO THE GRINDING AREA WHERE A WORKPIECE ISBROUGH INTO CONTACT WITH SAID ELEMENT, A HOOD PARTIALLY ENCLOSING SAIDGRINGING ELEMENT. A NOZZLE MOUNTED IN THE HOOD FOR DIRECTING A JET OFCOOLANT LIQUID AGAINST THE PERIPHERY OF SAID GRINDING ELEMENT WITHINSAID HOOD, A CURVED DEFLECTOR PLATE MOUNTED WITHIN THE HOODCONCENTRICALLY WITH THE GRINDING ELEMENT, MEANS FOR ADJUSTING THEPOSITIONS OF SAID NOZZLE AND DEFLECTOR PLATE, SAID MEANS FOR ADJUSTINGTHE POSITION OF SAID DEFLECTOR PLATE BEING EFFECTIVE TO ENABLE THERADIAL DISTANCE OF THE SPACE BETWEEN SAID DEFLECTOR PLATE AND THEPERIPHERY OF THE GRINDING ELEMENT TO BE VARIED AS THE DIAMETER OF SAIDGRINDING ELEMENT BECOMES REDUCED BY WEAR AND MEANS FOR SECURING THE SAIDNOZZLE AND DEFLECTOR PLATE IN THEIR ADJUSTED POSITIONS.